ACE and COVID-19: However, because RAASi—especially angiotensin-converting-enzyme inhibitors (ACEi) and angiotensin-receptor blockers (ARB)—have been shown to improve endothelial dysfunction, to reduce large artery wall thickening, and to regress smooth muscle cell hypertrophy in the past [25], a potential benefit of RAASi therapy in COVID-19 patients could not be ruled out so far.